Lec 22/23 Flashcards
Types of intercellular communication
Gap junction Transient direct link up cells Paracrine secretion Neurotransmitter secretion Hormonal secretion Neurohormone secretion
Intracellular chemical messengers
paracrines neurotransmitters hormones neurohormones (indirect communication b/t cells)
Endocrine
release of hormones that act far away from targets.
Paracrine
release of signalling molecules that act on nearby cells in the immediate area.
Autocrine
cell acts on itself ( by feedback )
3 modes of cell Communication
endocrine, paracrine, autocrine
a “wired system” with a specific structural arrangement. structural continuity in the system.
Nervous System
A “wireless system” organs widely dispersed and not structurally related to one another.
Endocrine system
System that requires neurotransmitters released into a synaptic cleft
Nervous System
System that requires Hormones released into the blood.
Endocrine system
System that acts a very short distance
Nervous
System that acts a long distance
Endocrine
System that depends on close anatomical relationship and not on specificity
Nervous
System that depends on specificity
Endocrine
System that is rapid, brief and precise.
Nervous
System that is slow and over a long duration
Endocrine
Which system has influence on other major control systems?
Endocrine and Nervous
Hormones
- regulate ion and water balance
- contribute to the response of external stress
- initiate steps in growth and development
- regulate the process of reproduction
- regulate the digestion, use, and storage of nutrients
- regulate the release of other hormones.*
Which endocrine glands soley affect endocrine function?
Pituitary
Parathyroid
Thyroid
Adrenal gland
What endocrine gland soley affects endocrine function and is a “regulator”?
pituitary gland
what are the regulator endocrine glands?
Pineal, Hypothalamus, Pituitary
What endocrine gland’s complete function is uncertain?
Pineal
What endocrine gland is a regulator and has a mixed function?
hypothalamus
Hypothalamus: target cells
Anterior pituitary
Pineal Gland: hormones
melatonin
Concentration of Hormones
10-9 to 10-12 molar (very low)
Activation of hormone receptors
effects of hormones are amplified, by the presence or certain hormone receptors a cell will respond to that hormone.
- alters channel permeability
- acts through second messenger system to alter activity of prexisting proteins
- Activates specific genes to cause formation of new proteins
Hormones : GPCR receptors
Parathyroid hormone (PTH)--> AC Arginine Vasopressin (AVP)--> PLC Thyrotropin-Releasing Hormone (TRH)-->PLA
Insulin :receptor
has a-subunit(disulfide bonds), binds to Tyrosine Kinase–> protein phosphorylation (growth and development)
Atrial Natriuretic Peptide (ANP): receptor
no alpha-subunit , binds to guanylyl cyclase –> cGMP
Growth Hormone (GH): receptor
1 a-subunit and 1 B-subunit , binds to JAK (janus kinase or just another kinase) Tyrosine Kinase domains. –> protein phosphorylation (growth and development)
Location: Steroid hormone receptors
act within the cell nucleus , but bind within the cytosol or nucleus.
Binding: steroid hormone receptors
activated steroid hormone receptors are bound within the nucleus or the cytosol and they bind to specific stretches of DNA called SREs, thus stimulating the transcription of appropriate geans
hsp
heat shock protein - hold steroid receptors.
SRE
stretches of DNA within the nucleus that are bound by steroid hormone receptors.
2 Types of Feedback Control
Simple Feedback Loop
Hierarchical control
Hierarchical control
a product regulates more than one enzyme.
Types of Hormones
Peptides, Amines (catecholamines&Thyroid Hormone), Steroids
Hormone Type: no aeromatic ring.
peptides
Hormone Type: Tyrosine derivative
Amines - Catecholamines & Thyroid Hormones
Hormone Type: Iodinated tyrosine derivative
Thyroid Hormone
Hormone Type: Cholesterol derivative
Steroids
Hormone Type: Hydrophilic
peptides, catecholamines
Hormone Type: Hydrophobic (lipophilic)
Thyroid Hormone, Steroids
Hormone Type: Synthesized Rough ER
peptides
Hormone Type:Synthesized in cytosol
catecholamines
Hormone Type:Synthesized in colloid
Thyroid Hormone
Hormone Type: Synthesized in intracellular compartments
from cholesterol –> steroids
Hormone Type:Stored secretory granules
peptides, Catecholamines (chromaffin granules)
Hormone Type: Not stored
Thyroid hormone, steroids (both released upon synthesis)
Hormone Type: mostly bound to plasma proteins
Thyroid Hormone, Steroids (partially catecholamines)
Hormone Type: free hormone (unbound)
peptides, Catecholamines (partially)
Hormone Type:receptor on Surface of target cell
peptides, catecholamines
Hormone Type: receptor inside target cell
thyroid hormone, steroids
Hormone Type: Activates specific genes to produce proteins
Thyroid hormone, Steroids
Hormone Type:Activates second messenger system to activate existing proteins
peptides, catecholamines
Hormone Type: from the hypothalamus, anterior pituitary, posterior pituitary, pancreas, parathyroid, gastrointestinal, kidneys, liver, thyroid C cells, heart
peptides
Hormone Type: only hormones from the adrenal medulla
catecholamines
Hormone Type: only hormones from the thyroid follicular cells
Thyroid Hormone
Hormone Type: Hormones from the adrenal cortex and gonads plus most placental hormones (kinda like VIT D)
steroids
Preprohormone
larger precursor peptides with a signal sequence at the N terminus of the peptide.
signal sequence
at the N terminus of a preprohormone that leads to the insertion of the growing peptide into the endoplasmic reticulum (ER)
prohormone
The structure following a preprohormone after the signal sequence is cleaved. When the prohormone is cleaved one or more hormones is made
Insulin formation: disulfide bonds
are formed when preproinsulin is cleaved to make proinsulin. They remain after proinsulin is cleaved to make insulin. (formed within the endoplasmic reticulum)
Synthesis of Neuropeptides : Basic AminoAcid pairs
common targets for processing enzymes (cleaving) LYS&ARG
LYS+ARG
common base pair for cleaving of neuropeptides
carboxypeptidase E
trims base pair AA resides of neuropeptides
peptidyl glycine a-amidating monooxygenase (PAM)
converts the carboxy terminus to an amide if the peptide ends in glycine.
Neuropeptides : Golgi
further modifications can be mades such as sulfation and phosphorylation takes place. 2 packaging schemes
- cleaved inside the released vesicles = 2 types of peptides
- cleaved inside golgi = sorted into separate vesicles
Synthesized directly from Tyrosine
3,4 - Dihydroxyphenylalanine (DOPA)
(Enzyme - Tyrosine hydroxylase)
(coenzyme - tetrahydrobiopterin BH4–>BH2)
tetrahydrobiopterin
BH4-BH2 coenzyme of tyrosine hydroxylase
Synthesized from DOPA
Dopamine
enzyme - DOPA decarboxylase
Synthesized from Norephinephrine
Epinephrine
(enzyme - phenethanolamine N-methyltransferase)
(coenzyme - adenyosyl-methionine –> adenyosyl - homocysteine)
Synthesized from Dopamine
Norepinephrine
(enzyme - Dopamine B-hydroxylase)
(coenzyme - ascorbic acid (reduced –> oxidized)
TH: feedback inhibited by..
Norepinephrine
MAO monoamine oxidase
breaks down NE into DOMA
breaks down Dopamine into DOPAC
(with aldehyde dehydrogenase (ADH) help)
aldehyde dehydrogenase ADH
breaks down NE into DOMA
breaks down Dopamine into DOPAC
(with aldehyde dehydrogenase (MAO) help)
Steroid hormones: mineral corticoid
Aldosterone (from Progersterone) [Both adrenal cortex]
Steroid Hormones: glucocorticoid
Cortisol [adrenal cortex hormone]
Steroid Hormones: androgen
Testosterone [male sex hormone]
Steroid Hormones: an estrogen
Estrogen [female sex hormones] made up of: Estradiol* Estrone Estriol
Steroid Hormones:
Cholesterol, Aldosterone, Progesterone, Cortisol, testosterone, Estriadiol
Regulation of Free hormone
tightly regulated by binding to plasma proteins
99% of hormones
exist in bound protein form
Hyposecretion
too little hormones
Hypersecretion
too much hormone (tumor)
Radioimmunoassay
Hormone quantification ; the process by which the concentration of hormones (in blood) or receptors (in tissue) can be measured using labelled hormones.
Saturation plot
hormone antibody complex [y] vs total labeled hormone [x] ; if you increase the number of hormones , you will increase the amount bound (competition) [SIGMOID] +
Displacement curve
labelled hormone bound to antibody [y] vs total unlabelled hormone [x] if you increase the number of hormones unlabelled, you decrease the number of labelled hormones. [linear negative]
Scatchard Plot
Bound steroid/free Steroid [y] vs bound steroid [x]
Slope = -1/Kd
where y = zero , is the total number of receptors